Telephone system



May 6, 1941. G. v. KING ETAL TELEPHONE SYSTEM .Filed ook.. 19, 19:59 11sheets-sheet 1 Q s m s .s Nu u s s n s?. n ...El N s S .um

. yw E E m M 0 @NA` 7 NR OC A KKH MAKWN. GER. S Wu R m N E V V W B 11Sheets-Sheer? 2 TELEPHONE SYSTEM Filed Oct. 19, 1939 I'Hl' G. v. KINGETA-L May 6, 1941.

RJr. Mc ALP/NE AUOQNEV l G. KiK/N6 /NVENTORS EA. KORN 'M-TWYM May6,1941- G.v.K|N'G mL 2,241,016

TELEPHONE-SYSTEM Filed Oct. 19, 1939 1l Sheets-Sheet 3 E n sIHb UJ\Q aal, G. u Irl/VG f /NVENTORS E .4. KORN By RJcMc ,4LP/NE w www May6,1941- G. KING ETA; 2,241,016

TELEPHONE SYSTEM Filed Oct. 19, 1939 11 Sheets-Sheet 4 l May 6, 1941.

G. V. KING ETAL TELEHONE SYSTEM Filed oct. 19, 1939 llsneetssheet 5 G.l( KING /VVENTORS RUR/V By Hc ALP/NE ATTORNAV May 6, 1,941. G. v. KING:TAL 2,241,016

TELEPHONE SYSTEM l Filed Oct. 19, 1939 l1 Sheets-Sheeb llr ATTORNEY G.v. KING r-:TAL

TELEPHONE SYSTEM Filed oct. 19. 1959 May 6, 1941.

FIRST SENDER LAS T SENDER GROUP-2 ATTORNEY May 6, 1941- G. v. K1N@ Em2,241,016

TLPHONE SYSTEM Filed oct. 19, 1959 11 Sheets-sheet 8 G. l( KING/NI/E/VTORS EAKORN R. K. Mc AL P/NE 5y ATTORNEY May 6,1941:G.v,K|NG`ETAL 2,241,016

TELEPHONE SYSTEM Filed Oct. 19, 1939 )1 Sheets-Sheet 9 n Hu , G. l( KING/VVENTOPS f. KORN RK. MC ALP/NE ATTORNEK May 6, 1,941. G. v. KING rs1-ALTELEPHONE SYSTEM Filed Oct. 19, 1939 11 Sheets-Sheet 10 G. VI KING E MNm m RU../ mn. A Ak. 2W SWU R mm N E ,VV,. WB

Mays 1941- G. V. KING ET AL 2,241,016

TELEPHONE SYSTEM Filed Oc'l'I-` 19, 1939 11 Sheets-Sheet '11 G. l( KING/NVENTORS F.' A. KOR/V RJK. MCALP/NE @y HMWMM ATTO/wf? Patented May 6,1941 TELEPHONE SYSTEM Gerald V. King, Chatham, Franklin A. Korn,

Elizabeth, and Roderick K. McAlpine, Rutherford, N. J., assignors toBell Telephone Laboratories, Incorporated, New York, N. Y., acorporation of New York Application October 19, 1939, Serial No. 300,140

20 Claims.

This invention relates to telephone systems and more particularly toarrangements for automatically connecting a large plurality ofconductors from one equipment to another.

Automatically responsive connectors are used in some telephone systemsfor connecting together two dissimilar types of equipment and extendinga large plurality of leads from one equipment to another. Connectors areemployed in order that these dissimilar types of equipment may beconnected together as required and thus a small numberof one type ofequipment may successively serve a large number of a different type ofequipments. Such arrangements are calculated on a holding time basis pertelephone connection. For example, if the average holding time for oneequipment is i-lve times as long as the holding time for anotherequipment, other things being equal, only one-fifth of the latterequipments are required and a connector may be used to connectthemtogether as required.

An arrangement having the above characteristics may be demonstrated inthe association of incoming senders with markers. The holding time ofincoming senders is comparatively long since, after the sender is seizedby a line or an operator, a number of separate operations take placesuccessively. The sender is iirst operated by pulses or othertransmitting devices according to the line connection desired. After theregisters of the sender are set a connector is seized and an attempt ismade to seize a marker through the actuation of this connector. Afterthe marker is seized registrations are transmitted from the sender tothe marker. The marker selects an outgoing trunk corresponding to theseregistrations and accordingly operates switches for completing theconnection andvthen releases. The incoming sender thereafter `maytransmit impulses to a distant cnice or to anoutgoing sender through theoutgoing trunk which has been selected by the marker. In most cases themarker and connector are released about the time theincoming senderstarts to transmit impulses to the distant oiiice or outgoing sender. Itmay thus be seen that the holding time for the connector and marker issmall compared to the holding time for the senders During busy oroverload periods of telephone calls the incoming senders often encounterdelays in obtaining the services of a marker since under the presentpractice a group of incoming senders have access to only one connectorbetween these senders and the group of markers. When a plurality oftelephone calls demand the services of a plurality of senders in onegroup, a connector vis seized by the sender iirst actuated and the othersenders in this group which have been actuated must await the completionof the operations in the marker before this connector is released. ThisnotV only adds to the holding time of the incoming senders but delaysthe completing time for telephone connections. In toll telephonepractice this delay is particularly serious in View of the added holdingtime for long and expensive toll lines and equipment involved in suchtelephone connections. Difficulties may also be encountered in the useof one connector available to a group of equipments such as senders, iffor some reason a fault exists in this connector. When this connector isremoved from service for test and repair, the group of senders must alsobe removed from service.

An object 'of the present invention is to minimize the delay inestablishing connections between individual equipments in two groups ofdissimilar equipments.

Another object is to enable a connector to be removed from servicewithout disabling the equipments served by the connector.

According to the present invention one connector is used between each ofa plurality of groups of equipments and a group of equipments common tosaid plurality ci groups in the same manner as previously practiced.That is: each group having a plurality of equipments therein has a firstchoice or preferred connector which may be actuated when idle forassociating an individual equipment in this group with an individual`equipment in the common group. An automatically operable system ofapparatus has, however, been provided in each connector so that eachconnector may be used by the equipments of another group as a secondchoice or alternate connector when 'it finds its own rst choice orpreferred connector busy. By using preferred and alternate connectorsaccording to the invention a connector is found available for usesubstantially all of the time which accordingly eliminates delays incompleting telephone connections.

A feature of the invention is a system having connectors forestablishing circuit paths between individual equipments in a pluralityof groups of equipments and individual equipments in groups common tothe plurality of groups, each group of equipments having one connectorwhich may be seized by an equipment in this group as the first choice orpreferred connector for this group or which may be seized by anequipment in another group as the second choice or alternate connectorfor this other group.

Another and related feature resides in the circuit arrangement of theindividual equipments in said plurality of groups and in the circuit ofthe connectors which automatically cause the actuation of an associatedidle alternate connector when the preferred connector for a group isbusy, the alternate connector being the preferred connector of anothergroup of equipments.

Another and related feature is in the auto-v matically responsive actionof the system in causing an equipment which has. found the. regularconnector busy and has seized. an alternate connector, to abandon thealternate connector i-f the regular connector becomes idle before thealternate connector has made a connection be tween two dissimilarequipments.,

Another and related feature is a system of associating a plurality ofequipments and a plurelity ef; Connectors a sequential order. mth theequipments. hai/.ine first and; second. choice ce@ Sarto 0.1.1.@Econnector. and; the next. in order @Queeg-tn'respectively.

Another and related feature isr a system of arranging the connecters` sothatthe. connector foro-a group o f eqgdipijnents may be. automaticallyQ1. manually removed from service: without. removing this group, ofequipments from service and for establishing the secondchoice oralternate connector. for this complete group of equipa mentsas the firstC hoiceconnector. f

nother, and related, feature.; is in. the ability of, ay connector ormarker to signal an equipment heine SSrVedWhen a. conneetioncannotbecompleted, thev signal; causing a. responsive adjustment'. in the;Circuit of. thisequipment. forY seizing the other connector to which ithas access` This may: be. the. first choice or the second` choiceconnector dependingv upon. the.-V connector originally seized forcompleting theconnection.

These and other features. will be discussed more fully in the following.description.

To illustratethe. features of. the invention reference may be had;to.the.accompanyingr drawingsin which:

Figs. LtoA 1l, when arranged as` diagrammatically. shown in Fig. 1,2,illustrate three connectors used; as. first choice or preferredvconnectors and second. choice or alternate. connectors between threegroups of senders and either a common group.' of toll: markers. or.. acommongroup` of localmarkers. The detailed structure of one sender-in..so.far. as.. is required. for operating the connectorA is showninFig. l.Thissender-and sender.. 4M indicatea plurality ofsenders forminga-group.AA second group of senders is-shownl in Fig. 7. anda thirdgroup-ofsenders is` shown ilLFig. 1D.. Fig. 2 illustratesithe apparatuslandcircuits of a. marker. required for completing connections from theconnectorsand senders General A description Three. groupsof senders,each having a plureality ofsend/ers therein are shown in Figs. 1, 4,7*'andj1'Q'. 'hekiirst sender of a group, herein known as group` 1 isshown in Fig. 1. The last senderofthis group is shown diagrammatically.as 41| vinFig. 4. The individual senders of this groupare associatedwitha connector disclosed inlEigs. 3,i 4- and 5, through a chain circuitwhich guardsagainst morethan one sender being asso- Qttedr. with ,theYconnectorat one time. The

choicefor preferred.l connector. serving this group of senders. Eachsender of the group may be associated with this preferred connectorthrough the contacts of a multicontact relay, such as H or 461. Theoperation of one such relay connects the conductors of a sender throughthe connector to either a toll marker or a local marker according to thecircuits established in the sender. The apparatus of the connector hasdifferentiating apparatus for selecting an idle marker. Each connectornormally prefers a particular marker but if this marker is busy theconnector selects another idle marker which may be any marker of thecommon group of markers.

The terrn common group of markers applies herein to either the group oftoll markers or the group of local markers. In certain instances onegroup of markers is used, which is known as a group of combined markerswhich serves either toll calls, or local calls. The first group ofsenders may also be served by the connector shown inFigs, 9, and 1l.Ihis connector. is the first choice; or-preferred; connector for thethird group of senders Hlilll-y to willv andY actsin the capacity of thesecond choice or' alternate: connector for the first-l group; ofsenders.. Forl this reason all of thev leads` from,v the senders ingroup` 1 are carried; through a plurality of multicontact relays M355`to 4131- toi the preferred connector and mi2 to Ild to the alternateconnector which includes as many multicontact relays in each of the twoconnectors as.. there aresenders in the group; With; this. arrangement,senderl No. 1 may eitherv be associated. with the connector; Figs. 3, 4and. 5, throughv the. operation of the connector start: relay 404 andtheA multicontact relay" i105.I or associated with the connector, Figs.9, 1Q and 1;l, through; the; operation ofthe connectorfstart.. relay|0123: and the multicontact relay, mi2. Theother sendersof group lareconnectecl in the samek manner. For example, the last sender of thegroup-may be associated with theY connector. of Figs.. 3, 4I and 5vthrough the operation. of. relays. lil'lV and' 401' and associated with.the alternate. connector by the-operation of relays 10.1.5. and |10 h1".Since each-connector prefersaI particular marker as-'rst choicethesender would ordinarily beV connected to adifferent marker throughthe. preferred connector than it would.Y through. thealternateconnector. If, however; in either casethepreferred marker is busyconnection.. couldf be made to the same markerv through. eitherconnector.

The.connector shown-in-Figs. 6, 'if and V isthe preferredl: or firstchoicei connector forthe secondgroupof; sendersY diagrammatcallyfshownas '5.0.0, andfll which includes-alarger plurality of senders. thanV isshown. The connector start relay 11M: and the .multicontact relay-105a-re actuated bysender 'HillY for connecting thesendentol its.preferred connector-extending'to the groupof toll' markers, 5.20 andFig. 2,- or the-groupof local markers.. diagrammaticall'y shown as 5 l6. If the preferred connectork for sender group -2, shownin Figs. 6, '7.and 8, is-indicated as lousy-the senders of. group 2 may ber connected.-to .their alternate connector, Figs. 3, 4and-5;` the-rst sender. 10|'being connected by the operation ofi the connector start relay M3 andthe multicontact relay 412; Likewisethe last and-intermediatesenders.of. this groupmay be 'connected' ton the. preferredV connectorby theoperation of connector start: relayv 'IBSand-the multicontact relayK'IITl or similar relays-- and-tothe alternate" connector by the`operation o f-Ay connector.- start relay 415i.' and the-multicontactrelay 414" or similar relays. As

previously stated the connector shown in Figs. 9, and 11 is thepreferred or first choice connector for the third group of senders whichincludes first sender |000, a plurality of intermediate senders notshown and last sender IO0I. The connector shown in Figs. 6, '7 and 8 isthe alternate connector for this group of senders. 'I'he rst sender ofthe group, |000, may be associated with `its preferred connector by theoperation of relays H104 and |005, and may be associated with itsalternate connector, Figs. 6, 7 and 8 by the operation of relays 'H3 and1l2. The last sender I00l in the third group is associated with itspreferred connector by the operation of'relay |001 and associated withits alternate connector by the operation of relays 1l5 and H4. From theforegoing, it is seen that the connectors are connected in a sequentialorder with the senders of each group having. a first and second choiceaccess to one connector and the next in order connector respectively.This represents one order of arranging the first and second choiceaccess of senders and connectors. Other arrangements are conceivablywithin the` scope of the invention.

The eciency of the connector arrangement according to the presentinvention has been calculated according to the holding time for suchconnectors Aand the probable time periods when either the preferredconnector or the alternate connector are available for serving sendersof a group. These calculations were made from actual experience withconnectors in use at the present time in which one connector is employedbetween groups of dissimilar equipments. These calculations show thatthe connector according to the invention has more than twice theefliciency of the connector now generally in use. Assuming the samedelays and the same holding time the connectors arranged according tothe invention can handle more than twice the nurnber of calls that thepresent connectors can handle. O1" in other words, the connector willhandle the same number of calls with less than half the delay time. Itmay be seen that this may be calculated from obtaining the over-all timethat each connector is used between a sender and a marker coupled withconsideration of the periods when a preferred connector is busy and thealternate connector is idle and the overlapping periods when bothconnectors are used at the same time..

As an example of the efficiency of this connector arrangement, let it beassumed that one sender in sender group I is taken for a telephone calland seizes the preferred or rst choice connector, Figs. 3, 4 and 5serving this group and that a second sender in .this group l is takenfor another telephone call. Finding the preferred connector busy but itssecond choice or alternate connector idle this sender in group I isautomatically steered to its alternate connector, Figs. 9, 10 and 11 andactuates this connector. This is the preferred connector for the sendersin group 3 and if a sender in this group is taken for a telephone callwhen the connector is serving a sender in group l the sender in group 3is automatically steered toits alternate connector in Figs. 6, '7 and 8.Since the connector in Figs. 6, 7 and 8 is the preferred connector forthe senders in group 2 a sender in this group which is taken for usewhen its preferred connection is thus engaged is automatically steeredto its alternate connector, Figs. 3, 4 and 5 which by this time isprobably idle. Thus according to calculations the senders of each group`will probably have access to either its preferred or alternateconnector for completing substantially all telephone calls.

An arrangement is provided for overload conditions whereby a senderfinding both the preferred and alternate connectors busy may use thefirst one yto become idle. If more than one sender in a group or groupsis awaiting the services of a connector the progressive order of seizureis the order in which the senders attempted seizure of connectors.

From the foregoing it is apparent that co. nectors according to theinvention facilitate the removal of one connector from service, ifnecessary, without the removal of a group of senders from service.Taking the connector, Figs. 6, 7 and 8, out of service would eliminatethis connectoras the preferred connector for the senders in group 2 andas the alternate connector for the senders in group 3. The senders of`group 2 are, however, now served by their alternate connector, Figs. 3,4 and 5, and the senders of group 3 are served by their preferredconnector, Figs. 9, l0 and 11. The senders of group Istill have accessto their preferred connectorFigs. 3, 4 and 5, and their alternateconnector, Figs. 9, l0 andll. Y

The alarm and ltrouble circuits, Figs. 3, 6 and 9, are arranged toautomatically switch an individual sender of a group .to its alternateconnector or switch the complete group of senders to the alternateconnector responsive to particular trouble conditions occurring in theassociated preferred connector` and operate signals to indicate ythetrouble.` A complete group of senders may also be manually transferredto the alternate connector. The connector is thus temporarily removedfrom service by automatically or manually operable means.

Detailed description The following detailed description is given for vthe connectors as associated with incoming trunk circuits, sendercircuits and markers in .a cross- .bar system of the character disclosedin patent `application King-McKim-Myers Serial No. 295,010, filedSeptember 15, 1939 or the patent application Busch-Scudder Serial No.295,012, led September 15, 1939. A connector of this character, however,may be used for connecting together dissimilar groups of apparatus ofany character requiring such connection. An incoming call entering atelephone office having equipment therein as -disclosed in theaforementioned patent application-s, actuates the circuits and apparatusof an incoming trunk circuit. A connection is made automatically fromthe incoming trunk circuit to a cordless operators position or incomingsender as fully disclosed in the aforementioned pat-ent lapplication toKing-McKinl- Myers or to an incoming sender as disclosed and describedin the aforementioned patent application to Busch-Scudder. An incomingsender is accordingly seized and the registers of the sender are setIaccording to signals .transmitted over the incoming trunk. -Such aregister is diagrammatcally shown as in Fig. 1. The contacts |02 :and|03 .are contacts on register relays which are connected together oneach call over a series circuit through other sender register relayswhen the send-er satisfactorily responds to the signals transmitted.This sender also has a plurality of class relays which are set throughthe apparatus of the incoming trunk or -from an operators pofor 'thepreferred and .alternate connectors.

sition to indicate to the sender the character of connection to beestablished,` that is, either a toll connection to a distant tollioceoraconnectionto a local oice Within thev area of thetelephone oilicehaving the equipment dis-closed. Ii the .telephone connection is to beextended to a distant toll of- -ce, contact |03 in the class register isclosed Vby the operation of a rel-ay having this contact thereon. Thisestablishes Ian operating circuit for relay I to indicate to the senderthat a-toll `marker is required for completing this connection. Thecontact is associated with a class relay for operating relay |09 toestablish circuits for the selection of ya local marker. Relay II 4 isoperated as a start relayr or off-normal relay to establish groundcircuit to apparatus ofthe sender, over a circuit established in .thecordless operators position equipment or automatically establishedl whenthe sender is seized. 'I'heoperation of the sender regi-ster relaysestablishes an obviouscircuit for relay I I3 from battery through itsWinding over a series circuit .through the register relays to ground oncontact 2 of the lowest number register relay. Relay |I3 establishes acircuit through its contact I, resistance-I I6, right Winding of relay||5 to -a contact on relay 305 The latter relay, When operated,indicates that the associated -connector is busy, when normal indicatesthat the associated connector-is idle Each connector has a relay suchvas 305,V 305 or 905, havingas many contacts as there are senders in eachgroup associated with the respective connectors. A separate lead, suchas lead I 32 connected through the right winding of relay II5, isconnected from the contacts of relays 305, 605 and 905 to a like relayin each sender. Relay I I 5 remains normal if relay 305 is normal in.the associated connector .but operates when it findsthis relay operatedwhich indicates that the connector is busy. Leads |30 and |3I tracedthrough the contacts of relay II5 .are the start circuits Lead I3I isthe stant circuit forthe preferred connector, Figs. 3, 4' and 5, whichestablished when relays 305 and Il I5 are normal and consequently theconnector is idle. Lead |30 is the start circuit for the alternateconnector, Figs. 9, and lil, lestablished automatically by th-e sender'yand connector when the preferred connector-is found busy. Circuits forthese lead-s- Will be described after other circuit paths havebeenestablished in-.thesenden rllhe `operation of relay I I3 aspreviously described, establishes-a circuit through its Contact 2 foroperating relay |01. ThisA circuit may be traced from ground .throughcontact I o'f'relay I'I4,.con-tact 2y of relay I-I3,' Contact I ofeither relay |00'A or |10, contact Iof relay |048 to battery through theright Winding of relay |0'1. The operation of' relay |01 establishes acircuit from battery .throughv its contact 2, contact Tof relay I 08,contact 2. of relay I I 8 .thence over either leads' |36v or |31.depending upon Whether a toll marker o'r .a local marker is to beselect-ed.y For this example, it may be assumed tah't a toll marker isdesired and relay I I0 was operated through contact` |06of theclassregister. A circuit isthus established from ground' on contact 2 ofrelay |09, normal, through' contactZ ofrelay I I0, operated,`left-Winding of relay I1|8 to` battery, operating t'he latter relay.The' circuit previously traced from battery .through contact 2- of relay|01. istlius extended over conductor |30 to contact 8 .oi the connectormulticontact relay' 405;. relay' has not as' yet been operated andtherefore thel type of marker to be used will be selected later.

For the first actuation of a connector it will be assumed that the firstchoice or preferred connector shown in Figs. 3, 4 and 5 is idle andtherefore a circuit is not completed for the operation of relay |I5.With relay |01 operated the connector is-seize'd overV a circuit whichmay beI -traoed' from battery through contact 2 of'relay |01,` contact Iof relay II9, contact 2 o-f relay |08', contact 4 of relay I'|1, contactI of relay I` I5, normal start lead Ir3I, contact I of relay 309,Winding of relay 404 to ground through the winding of relay 3I3. Relays404 :and 3| 3 operate in the circuit traced'. Relay 404 establishes acircuit for the multicontact connector relay 405. This circuit extendsthrough a` chain of contacts on' `the start relays such as relay 404associated with all' of the senders of tWo groups, one group of' senders(group l) having this connector as a preferred or regular connector andthe other group of senders (group 2)y having this connector as analternate connector. Relays 404 and 406 are .connected with the iirstand last senders of group 1 with like relays connected to intermediatesenders. Relays 4|3 and 4I5 are connected with the rst and last sendersof group 2 with like relays connected to intermediate senders. Thecircuit for relay 405 may thus be traced from ground on contact I ofrelay 4 I 5, normal, through contacts of intermediate relays, contact Iof relay 4I3, normal, which are associated with senders having thisconnector as an alternate connector, thence through Contact 3 of relay406, normal, contacts .of intermediate relays, contact 3 of rel-ay 404,winding of relay 405, contact 3 ofrelay 358,Y Contact I of relay 309,lead I3I, con- .ta-ct I of relay I I5, contact 4 of relay II1, contact 2of relay |031, Contact I of relay II9- to battery through contact 2 oirelay I 01.

The operation of relay 405 establishes a locking'V circuit for itselfthrough its contact I and connects all the leads from the sender throughits contacts and establishes circui-ts for the connector relays, Fig. 5,for associating the first sender ci group I with an idle marker. Groundthrough its contact 2 is connected to the armature of'Y interrupter 30|for establishing a timing circuit. This timing circuit will be explainedlater. Ground through contact 5 of relay 405 establishes a shunt forrelay II5 of the sender. Assuming that the preferred toll marker is idlethe marker preference relay 50| is now operated over a circuit fromground through its Winding, contact 2' of relay 500, lead 520, contact 8of relay 405; lead |35, contact 3 of relay II8, contact 2 of relay |08,contact I of relay IIS, to battery through contact 2 of relay |01. Thesame character of relay associated with a local marker would' have beenoperated overrlead |31 and contact 9 of relay 405 if relay |I8 of thesender remained normal. Relay 50| in operating establishes' a lockingcircuit for itself through its contact 4 to ground and opens theoperating circuit for all' similar relays 30| and IIOI in otherconnectors associatedwith this particular marker. Relay 50| places abusy condition on the connector by establishinga circuit through itscontact 5Y for busy relay 305'. The operation of relay 305A connects abusy ground to all senders associated With this connector. This groundextends to all of the sendersin group I as shown for sender No. I overlead |32 through the Winding of relay I'I'5`, resistance I|6 to* contactIA on relay II3`. Any sender of this group attempting to seize thisconnector will now operate a relay the same as relay H5 which Will causethe actuation of the alternate connector for this group of sendersover astart lead the same as lead |30 in a manner to be described later. Theoperation of relay 50| also establishes a circuit for relay 502 frombattery through its Winding, contact I of relay 50|, contact` of relay80|, normal, to ground through contact of relay normal. The operation ofthe multicontact relay 502 connects the sender leads which have beenextended through the multicontact relay 405 to contact of relay 502 andto the apparatus of the marker. This includes conductors extending tothe marker registers and the conductors which are shown. The circuitsestablished by contacts and 6 of relay 502 will be covered in thedescription of the circuit disclosed in Fig. 3. Contact 8 of relay 502establishes the marker as busy to ell other connector circuits byoperating relay 203 in the marker. The circuit for this relay may betraced from ground through contacts land 8 of relay 502, winding ofrelay 203 to battery. The operation of relay 20L establishes a circuitfrom ground through its contact, right winding of relay 500, resistance5|4 to batery. Relay 500 in this connector, however, does not operatesince a shunt circuit is placed around this winding of relay 500 fromground through contact 1 of relay 502, contact 2 of relay 50|,terminating between resistance 514 and the windingof relay 500. Theground from the contact on relay 203, however, extends through the rightWinding of relay 800, resistance 8|4 to battery and the right winding ofrelay H00, 'resistance |||4 to battery associated With the same markerbut in other connectors. Since relays 80| and ||0l in the otherconnectors are not operated no shunt is placed around'the right windingsof relays 800 and |00 and, therefore, these relaysare operated. Withrelays 800 and ||00 operated, the circuits for seizing markers in theconnectors shown in Figs. 6, '1, 8 and 9, 10, 11 are extended to anothermarker seizing relayl For exampleglead 820 is used for seizing a markerin the connector, Figs. 6, '1 and 8. With relay 800 normal', a circuitis established for marker'seizing relay 80| but with relay 800 operatedthe circuit is extended to marker seizing relay 8| for seizing anothermarker.

The marker has a timing circuit 2|0 to guard against failures, operatedby the release of relay 205 Which is normally maintained operated. Thecircuit for relay 205 extends through contact ,'4 of relays ||0I and 80|to ground through contact 44 of relay 50|.` The operation of relay 50|releases this relay which establishes a circuit for the timing circuit.This may be any Well known character of timing circuit such as used formarkers `which cause the release of the marker or the operation of atrouble indicator whenthefmarker and connector have been maintained inan operated position longer than is required for completing :theirfunctions. Relay 201 in the marker is' an oir-normal relay operated frombattery through its Winding, contact 3 of relay '50| to ground onContact 3 'of relay 405. This relay establishes a `locking circuitthrough its contact t-o the operating ground and establishes a numberofcircuits (not shown) for the operation of marker apparatus. A senderthus connected to a marker through the connectors, Figs. 3, 4 and 5,transmitsv registrations for preparing theV marker to select an outgoingtrunk in a particular toll group of trunks and for operating theswitches to connect the selected outgoing trunk with the callingincoming trunk. rTests assuring the satisfactory operations of themarker establish a circuit for operating relay 208. The operation ofrelay 208 completes a circuit for operating the marker release relay 202which opens marker circuits not shown and locks to a plurality of pathsto assure the release of all apparatus of the marker. A circuit is alsoestablished for relay H9 of the sender for opening the connector startcircuit. The operating circuit for relay ||9 may be traced from batterythrough the winding of relay ||9, contact 1 of relay 405, contact 2 ofrelay 502, contact 2 of relay 202 to ground through contact 2 ci relay201. The connector start circuit previously traced over lead |3| isopened by the operation of relay ||8 which releases relays 404 and 405which were held operated to battery from contact 2 of relay |01. Therelease of relay 405 opens the operating circuit for relay 50| and thelocking circuit for relay 201, and both relays release. The release ofrelay 50| opens the operating circuit for relay 502 and the operatingcircuit for the connector busy relay 305. The release of relay 305 makesthe connector available for seizure by another sender. The marker is notmade available for seizure by another connector until relay 202 releasesindicating that all apparatus of the marker has been satisfactorilyreleased. Relay 202, as indicated by the dotted line, is maintainedoperated through a series of contacts of relays which must releasebefore relay 202 can release. Relay 203 is maintained operated throughits contact to ground on contact 3 of relay 202 so that this marker willnot be seized until it is in proper condition for seizure. The releaseof relay 50| opened the shunt circuit which maintained relay 500 in anormal position. Relay 500, therefore, now operates `to ground oncontact 2 of relay 203. Relays 900 and l |00 in the other connectorsdisclosed also remain operated until relay 203 is released. It is seenthat these relays hold the operating circuit for relays 50|, 80| and||0| open so that this marker cannot be taken to use. The release ofrelay 202 releases relay 203 which opens the operating circuit forrelays 500, 800 and ||0|, preparing the marker circuit for seizure byany connector. The left-hand Winding of relays 500, 800 and H00, alsorelays 5|0, 8|0 and |||0, are used as for locking the relay in positionif a relay, such as 402, is operated before the release of these relays.For example, the locking circuit for relay 500 extends from batterythrough its left winding and contact I to Contact of relay 5|0 to groundon contact 4 of relay 405. This circuit is only established if afterrelay 205 is released and before thel relay, such as 500, is released,the connector is seized for selecting a marker. This selection shouldproceed to conclusion without interference and therefore the relayremains locked until this marker is made busy. The ultimate operation ofthe relays, such as 5| 0, associated with another marker in thisconnector and other connectors releases the holding circuit previouslyestablished.

Timing and trouble circuit The timing and trouble alarm circuit shown inFigs. 3, 6 and 9 associated with each connector functions to guard eachoperation of the connector so that if any trouble whatsoever isencountered a signal is immediately given to indicate that some part ofthe vconnector has a fault therein. of aA connector causes the operationof relay 3I3V in the alarm circuit. The operatingcircuit for relay 3I3is in series with relay 404 or any like relay associated with theplurality of senders in the group of senders which use this connector asa preferred connector and also in the group of senders using thisconnector as an alternate connector. VEach relay 404, 400, 4I3, M5, 405,401, 4I2 and 4M and the intermediate relays connected with the sendersof two groups have separate operating circuits through the contacts ofrelays 303, 309, 3I4 and SI5. The operating circuit for the relaysassociated with senders using this connector as the preferred connectorextends through the contacts of relays 300 and 300. The circuits forrelays associated With the senders using this connector as an alternateconhectorV extend through the contacts of relays 3I4 and SI5. TheVKcircuits referred to are the same as previously traced for connectingthe sender, Fig. l, With 'the connector, Figs. 3, vl and 5. Theoperation of relay 3I3 connects `ground tothe moving member ofinterruptor 30|. This member of the interruptor has a slow movementWhich allows a maximum vtime for the operation of the connectorapparatus. This interruptor iirst closes its contact 2 to establish acircuit for relay 303 from battery through its winding, contact 2 andthe moving member of interruptor 30I', contact of relay 3I3, contact 2of relay SI2. contact 3 of relay 3H to ground. Relay 303 operates overthe circuit traced. After a period of time the interruptor closes itscontact i which establishes alcircuit for relay 301 from battery throughits left winding, contact I of relay 303, conta-ct I of the moving,member of interruptor 301, contact of relay SIS, contact 2 of relay3I2, Contact 3 of relay 3II to ground. The operation of relay 301immediately lights lamp 3IS to indicatey a fault-in the connector andestablishes an obvious circuit for operating relays 300 and 3I4 Whichopens the operating circuit forvconnector multicontact relays 405, 301,4I 2 and 4I4. If the sender end of the Iconnector cirsuit, functionssatisfactorily there is insufficient time Vfor the operation of relay301 through the contacts of interrupter 30|. Assuming that relay 405 wasoperated satisfactorily, a second circuit is established for the timinginterrupter StI to insure the operation of this timing circuit if relay3I3 failed to operate. This circuit may be traced from ground on contactk2 of relay 405, contact I of relay SI2 Vto the moving member Vofinterruptor Sill. When relay 502 is operated during progressiveoperations in the connector, a cir-cuit is established for rela-y 32 andalso for interruptor 302.' This circuit may be traced from ground oncontact 5 of relay 502 to the moving member of interruptor 302 and tobattery through the Winding of relay SI2 operating the latter relay. Theoperation of relay SI2 opens the circuit established for interruptor 30Iand starts a second series of timing which replaces the rst series koftiming events. This is also a slovv moving interrupter which allows themaximum time for subsequent operations in the connector and marker. Acircuit is first established for relay 304 from battery through itswinding, contact 2 and movi-ng member of interruptor 302 to ground oncontact 5 lof relay 302. If sufcient time elapses the moving member ofinterruptor 302 makes contact With its contact I and establishes acircuit through the Contact 2 of relay I 004, Winding As previouslystated the seizure right Winding of relay 301 which, as 'hereinbeforcstated, establishes a circuit for lamp {H0-and a circuit for relays 308and 3M. The operation of relay 301, therefore, serves to indicate eithertrouble in the connector or that the connector was unable to obtain theservices of a marker and also may indicate `trouble in the marker Whichmaintained the operation of the connector a longer period .than requiredto complete thc normal Yfunctions in making a telephone connection.Relay 301 establishes a locking circuit through either Winding and thecontacts 3 and 4 associated therewith to the ground circuits used forvoperation through either interruptor 35i Second choice or `alternateconnector Whenever the preferred connector ,is found busy..

An individual sender of a sender group is transferred to the alternateconnector under certain conditions when a fault exists in the preferredconnector. Under another condition Where a fault exists in the connectorwhich makes it impossible to function, a complete group of senders isautomatically transferred to the alternate connector and the preferredconnector is automatically temporarily removed from. service 0r madeunavailable for use. A connector may also be removed from service by amanual operation which transfers all of the senders using this connectoras the Vpreferred connector, to the alternate connector.

When the individual sender of a sender group attempts to seize thepreferred connector and iinds this connector busy the circuits areadjusted to automatically transfer this sender to the alternateconnector. As previously stated, a connector is indicated as busy to allof the senders in a sender group by the operation of rel lay 305 for theconnector, Figs.V 3, 4 and 5, by relay 605 for the connector, Figs. 6, 7and 8 and by relay 905 for the connector, Figs. 9,10 and l1. Theoperating circuit for relay 305 may be traced from battery through itswinding to ground on relay It will be remembered that relay 50| operatesfor seizing a particular marker through the contacts of themulti-contact relay 502. Assuming that the sender, Fig. 1, attempts toseize the connector, Figs. 3, 4 and 5, When it is busy, a circuit isestablished for relay II5 from ground through contact I of relay 305,conductor I 32, right winding of relay II 5, resistance IIS to batterythrough contact I of relay I I3. The latter relay Was operated throughthe register relay contacts when the sender was actuated?. Relay I I5 inoperating establishes a locking circuit for itself froml battery throughits left winding and contact 3 to ground through contact 5 ofmulticontact relay 405, which latter relay is operated since thisconnector is busy..

The operation of relay II5 transfers the start circuit from conductorI3I to conductor |30. The start circuit for the second choice oralternate connector may thus be traced from battery on contact 2 ofrelay |01, Contact I of relay IIB, contact 2 of relayI08, contact 4 ofrelay II1, contact I of relay H5, lead |30 which extends through Figs.3, 6 and 9, contact I of relay SI5, Winding of relay I0! 3, contact 2 ofrelay 9I3 to lof relay |006,-

ground. Relays |I3 and 9|3 operate in the circuit traced. Relay 0|3starts the alarm circuit for timing the operation of the connector,Figs. 9, and 11,` as previously described for the alarm circuit, Fig. 3.Relay |0|3 establishes a circuit for the multicontact cut-in relay |0|2for associating the first sender, Fig. 1, of sender group l with theconnector apparatus, Figs. 9, 10 and 11. The circuit for relay |0|2 maybe traced from ground through contact of relay |0|5, contact of relay|0|3, Winding of relay |0l2, conductor 962, contact 2 of relay 9|4,contact I of relay 9|5 and thence over lead |30 to battery throughcontact 2 of relay |01 as traced for the operating circuit of relay|0|3. A circuit is thus established for the marker preference relaywhich may be either I|0| or HH or an` intermediate relay depending uponwhich of the markers are idle and available for seizure. For

this example, it may be assumed that the marker,

Fig. 2, is busy, which, as previously describedl, Will cause theoperation of relay H00. If the marker 520 is idle, a circuit isestablished for relay HH. A circuit for relay HH may be traced fromground through its Winding, contact 2 of relay HIB, normal, contact 2 ofrelay H00, operated, conductor I |20, contact 4 of relay |0| 2, lead|36, contact 2 of relay H8, operated, contact 2 of relay |08, normal,contact of relay l I9, normal, to battery through contact 2 of relay|01. The operation of relay HH establishes an operating circuit for themulticontact marker cut in relay H|2 from battery through its Winding,contact of relay HH, contact l of relay 5H to ground on contact I ofrelay 8H. The chain circuit through these marker preference relaysestablishes the fact that no fault exists in the apparatus for seizingthis particular toll marker 520. The operation of relay |||2 thusassociates the sender, Fig. 1, with the toll marker 520 which may beassumed as the same character of marker as shown in Fig. 2. Aspreviously described, this establishes a circuit for relays 5|0 and 8|0in the connectors, Figs. 3, 4 and,5, and 6, '7 and 8 so that theseconnectors will not attempt to seize the marker 520. A shunt Was placedon relay 0 so that this relay in the connector being used for seizingthis marker, is not operated.

In order that the telephone connection may be completed when a fault isencountered in a connector preceding the seizure of a marker, la signalis transmitted to the sender which adjusts the apparatus of the senderto obtain the services of its alternate connector. This fault may occurin any part of the connector circuits and apparatus up to the operationof the marker cut-in relay such as relay 502. As previously stated theoperation of relay 301 from interrupter operates relays 308 and 3| 4when a fault prevents a connector from completing its function. Theoperation of relay 308 establishes a circuit for relay 306 from groundon contact of relay 308, right Winding of relay V306 to battery. Acircuit is thus established for relays 300 and 3| A circuit for theserelays may be traced from ground on contact 4 of relay 3|2, contact 4 ofrelay 306, contact 2 of relay 301 to battery through the right Windingof relay 300 and to battery through the Winding of relay 3| Relay 300 islocked to ground on key 3|6 through its right Winding which alsoestablishes a locking circuit for relay 3| l. A circuit is thusestablished for relay |08 in the sender from battery through itsWinding, contact of relay H1,- lead` |38, contact |0 of relay 405,contact 2 of relay 306, con.

tact of relay 301, contact 6 of relay 3| l, contact 3 of relay 3|2,contact 2 of relay 308 to ground on contact of relay 3|4. The operationof relay |08 opens the operating and holding circuit for relay |'01which releases and causes the release of relays 404 and 405. The releaseof relay 405 opens the operating ground for relay |08 which also removesa shunt from the operating circuit of Vrelay H1. With this groundremoved relay H1 operates in series with relay |08. The circuit foroperating relay I I1 extends from battery through the Winding of relay|08, left Winding of relay H1, contact of relay |08, contact of relay||0, cont-act 2 of relay H3 to ground on contact of relay H4. Theoperation of relays |08 and H1 changes the start circuit from lead |3|to lead |30. An attempt is now made to seize the alternate connector sothat the telephone call may be completed. A locking circuit isestablished for relay H1 from battery through its right Winding andcontact 2 to ground on contact 2 of relay H4. The operation of relay I1estab- -lishes a circuit for the reoperation of relay |01 from batterythrough its right winding, contact 5. of relay H1, contact of relay I0,contact 2 of relay H`3, to ground on contact of relay H4. With relays01, |08 and H1 operated, the start battery is established for thealterna-te connector .start circuit. This start circuit may be tracedfrom battery through contact 2 of relay |01, contact of relay H9,cont-act 2 of relay |08, contact 3 of relay I1, contact 2 of relay H5,normal, lead |30 which extends through Fig. 3 and Fig. 6 through contactof relay 9|5, the winding of connector relay |0|3, contact 2 of relay|006, contact 2 of relay |004, Winding of relay 9|3 to ground. Theoperation of relay I0|3 thus associates the connector, Figs. 9, 10 and11, With the sender of group I as traced and establishes a circuit forthe multicontact connector relay |0|2. 'I'his circuit may be traced fromground on contact of relay |0|5 through contact l of relay |0|3, Windingof relay |0|2 over lead 952, contact 2 of relay 9|4, contact of relay9|'5, lead |30, contact 2 of relay H5, contact 3 of relay |1, contact 2of relay |08, contact of relay |9, contact 2 of relay |01 to battery.The operation of relay |0|2 associates the sender, Fig. 1, With theconnector apparatus of Fig. 1l in the same manner as previouslydescribed and in the saine manner that the operation of relay 405associated the sender with connector apparatus of Fig. 5. The sameoperations as previously described may be assumed for this connectionand consequently the alternate connector is operated for associating thesender with a toll marker. Relay H0| is therefore operated from groundon contact 4 of relay 50|, contact 4 of relay 80|, Winding of relayHOI', contact 2 of relay H00, contact 4 of relay |0|2, lead |36, Contact3 of relay H8, cont-act 4 of relay H1, contact l of relay H0, contact 2of relay |01 to battery. The operation of relay ||0| establishes acircuit for relay H02 from ground on contact of relay ||`0| to batterythrough the Winding of relay H02. The operation of relay H02 associatessender, Fig. 1, With the marker, Fig. 2. The subsequent operations inthe marker and in the connector are the same as previously described andneed not be repeated. It will be remembered that relay H5 is operatedbythe preferred connector When a sender attempts to seize this preferredconnector after it has been taken for use by another sender. The

alternate connector start lead is thus actuated that this is the firstattempt te .obtain connection with a marker and a fault is encountered;a circuit is established by the alternate connector for operating relayi138 from ground on relay 914 over a circuit through apparatus ofthealternate connector, the same as previously traced from ground on thecontact of relay I@ when a fault WasV encountered inthe preferredconnector. The operation of relay W8 establishes a locking circuit. forrelay Itv and releases the apparatus of theV alternate connector in thesame manner as described for the preferred connector. The shunt is thusremoved from relay IIT which operates in series with relay |108 forVactuating the preferred connector start circuit. Under normalconditions. the` latter connector Would,V after this interval; of time,be free for use in completing the connection to a marker and will beseized by the sender and operated in the manner described above.

' A complete groupY of senders may automatically be transferred to thealternate connectors when a particular type of fault is found in aconnector. rIhis .fault may be either a ground on the connector multipleassociated With lead 320 or 32|, A ground accidentally associated witheither of these leadsV establishes an operating circuit for grouptrouble relay 305 which in operating locks through its right Winding toground on key 3I'6. This; ground extendsv through the contact of relay300, winding of relay 3l I to battery which operates relay 3l I. Theoperation of relay 3II establishes energizing circuits for connectormakebusy relaysY 309 and 315. A circuit for relay 309 extendsV frombattery through its Winding, ycontact I of relay 3| I to ground oncontact 5 of relay 301-. The circuit for relay SI5 extends from batterythrough its'winding, contact 6 of relay 306, Contact I of relay 3H toground on contact 5 of relay 331. The operation of relay 309 opens allof the start circuits for the iirst choice connector relays, such asrelays 404 to 403, associated with the senders of sender group I. Thesestart circuits are represented by leads I3I from the rst sender in thisgroup and lead MI from the last sender in this group. `These startcircuits ordinarily used for actuating the rst choice connector, Figs.3, 4 and 5 are novv transferred to leads 133 and 651 extending throughthe armatures and inside contacts of relay 359, normal contacts of relay9i'5 for energizing start relays |013 and i015 and the intermediaterelays Whenever the senders of group I attempt to seize a connector.

' Consequently, in this instance the sender in energizing the circuitwhich Would ordinarily actuatethe preferred connector establishes acircuit for the alternate connector and does not have any path forenergizing the preferred connector. In the sender under' thesecircumstances, the arrangement of transferring from a preferred to analternate connector is made useless since no circuit is established forenergizing relay II5. The operation of relay 31'5 opens the secondchoice start circuits 150 to I'rl from the senders in sender group 2 toconnector start relays 4I3 to lil'in order to remove this connector assecond choice or alternate connector for these senders.

Y' `Theabove condition fer transferring a comlishes circuits for relays369 and 315 from battery through their windings to ground on the and thelatter connector semed if idle. Assuming' sleeveof jack 3m'. Thistransfer is made when a connector is removed fromvservice in order thatthe senders of the group may continue to function in the normal mannerusing theV alternate connector instead of the preferred connector. Inthis case the senders of group I only function through the alternateconnector and the senders of group 2 function through their preferredconnector during the period of time that this connector is removed fromservice. Plug 625 is inserted in jack SII! for operating relays 609 andSI5 to transfer the senders of group 2 to the alternate connector whichin this case is the connector, Figs. 3, 4 and 5. Plug 925 is inserted injack 910 to operate relays 963 and 9i5 when the connector, Figs. 9, 10and 11, is removed from service so that the senders in group 3 may usethe alternate connector which in this case is the connector shown inFigs. 6, 7 and 8.

In order to facilitate the tracing of circuits for energizingv theapparatus of `the preferred connectors or the alternate connectors thefollowing table is given showing the leads to follow for associatingeither connector With the senders of Ithe different groups. In each casethe lead given is associated with battery over a circuit in the senderthrough a contact, such as contact 2, of relay IUI. The preferredconnector or the alternate `connector is energized in the mannerpreviously described over thesev leads.

Preferred connector Alternate connector Start rcircuit Y Cut-iu relaycircuit Relay l Relay Lead operated Load Lead' operated Firstsender-Group l 130 1013 130 962 1012 Last sender-Group 1 451 1015 451063 1014 First sender-Group 2. 750 413 750 362 412 Last sender-Group 2.751 415 l 363 414 First sendcr-Group 3. 1050 713 1050 662 712 Lastsender-Group 3. 1051 71o 1051 663 714 Under the condition Where a senderfinds the preferred connector busy and a circuit is established for `theoperation of relay II5 in order` to associate the sender with thealternate connector, the condition may be changed if the preferredconnector becomes idle before the relays ofthe alternate connector areoperated. It will be remembered that after the test of the connector ismade other operations occur in the sender before the connector startcircuit is established. This causes a short interval of time duringwhich the preferred connector could have become idle. When relay II5 isoperated to automatically steer the sender to the alternate connector alocking circuit is established through contact 3 of relay II5 to groundon contact 5 of relay 495 in the busy connector. This, of course,applies to any sender of any group as Well as any connector, the circuitbeing the same in all senders and in all connectors. If the conj'becompleted because ofv a fault in the marker or nection proceeds to theseizure of the alternate connector a locking circuit is establishedlnthe alternate `connector for relay H5. Since the connector shown inFigs. 9, 10 and 11 is the alternate connector for the sender showninFig. 1, this locking circuit may be traced to ground on contact 1 ofrelay |0|2 this relay being operated for use as the alternate connecteI,f'how ever, preceding the operationof relay ||2 the connector, Figs.3, 4 and 5, becomesidle, relay 405 is released and thusthere is nolocking circuit for relay and, further, there is nooperating circuit forrelay ||5 since relay 305 has been released.V In this case relay|'|5releases and a circuit is established for seizing the preferredconnector, Figs. 3, `l and 5, and the circuits to the alternateconnector,` Figs. 9, l0 and 1l, are opened. It may be seen, however,that if the circuit connection is established for relay |0|2 thealternate connector is used even though the preferred -connector becomesidle a moment after the operation of relay |0|2 since the operation of`this relay establishes the aforementioned locking circuit for relay||5.

Marker When for some` reason, thesmarker, ,F.g, `2, can not complete itsoperations according to the registrations, the timing circuit 2|0operates .the second trial relay 200. This relay connects ground to alead extending through contact .4 of the connector multicontact relay502, 802 vor |02. Assuming that this circuit was Vestablished throughcontact 3 of relay 502 it thus extended through contact |0 of relay 405,contact Vof relay I|1, winding of relay |08 to battery. Relay |08operates in the circuit traced and the operation of relay |08 opens thestart circuit for the connector and the operating circuit for `relay |01which releases. Relays 405 and 404 release which causes the release ofrelays 50| and 502. The

ground circuit for operating relay |08 is thus opened which removes ashunt path for relay I1. The latter relay now operates in series withrelay |08 from battery through the Winding of relay |08, left Winding ofrelay '||1, contact I of relay |08, contact of relay ||0`, contact 2 ofrelay |I3 to ground on contact of relay H4. The operation of relays |08and ||1 reestablishes the circuit for relay |01 from battery through itsright winding, contact 5 ofrelay .|l1, contact of relay ||0, contact 2of relay ||3 to ground on contact of relay H4. The operation of relay|01 now establishes a start circuit for vthe alternate connector whichmay be traced from battery through contact 2 of relay |01, contact ofrelay H9, contact 2 of relay |08, contact 3 of relay |11, lead |30,contact of relay 915, winding of relay |0|3 in the alternate connector,contact 2 of relay |000, contact 2 of 'relay |004, Winding of relay 9|3to ground. The alternate connector is thus energized to seize a markerin an Veiiort to complete the telephone connection which could not becompleted by the marker originally seized. Under this condition if thealternate connector is busy relay |5 is operated and the sender wouldmake its second choice over the preferred connector since the operationof relay ||'5 alters the choice of connectors as previously described.Conversely, if the alternateconnector has been chosen for the firsttrial, sender relay I5 4was operated for energizing this connector toassociate a marker therewith in an attempt to ,select an outgoing trunkand complete a switching connection. Assuming that this `connectitmcannot associated equipments, a circuit is established by the'marker forsignaling the sender to make a second trial as outlined above. Thiscircuit operates the sender relay |08 as previously explained, whichestablishes a locking Kcircuit for rel-ay `||5,` vreleases the connectorrelays by removing Y the alternate connector start circuit. Relay ||1 isoperated as soon as the connector ,shuntground is removed from -its leftwinding and relay |01 -is again operated to reestablish the connectorstart circuit for actuating the preferred connector from battery throughcontact 2 of relay |01, contact of relay k| I9, contact 2 of relay |08,contact `3 of relay ||1, contact 2 of relay ||5 Ito lead |3| `Whichextends to the preferred connector relays as previously traced.

'I'he `apparatus fOr associating a sender with a local marker is thesame as shown in Figs. 5, 8 and 10 and is thus diagrammatically shown at5|5, SI5 and |||`5 since it is believed unnecessary torduplicatc thedisclosure of the circuit and apparatusinvolved for associating a senderwith a local marker. As hereinbefore stated a local marker is seizedwhen relay |09 is operated and relay ||0 remains normal. This causesrelay ||8 to remain normal and therefore the circuit for the markerpreference relay, such, for example,

`as relays 502iand 5| I, which are in the selecting circuit .of theconnector for selecting a local marker, is established over lead |31instead of lead |36. This may be traced from battery through contact 2of relay |01, contact l of relay US, contact 4,2 of relay |08, contact 3of relay ||8, normal, lead |31, .contact 9 of relay 405 `which extendsto the local marker connecting reother group having a plurality ofindividual electrically operable equipments therein, connectors forestablishing circuit paths between individual equipments of saidplurality of groups and individual equipments in said .other group, thenumber of connectors being equivalent to the number of groups in saidplurality of groups, and means in the equipments of said plurality ofgroups automatically energized by means in said connectors `forcontrolling the choice of a connector for completing circuit pathsbetween said individual equipments.

2. In a control system for establishing `electrical circuit paths, aplurality of groups Vof individual electricallyoperable equipments, each`group comprising a plurality of said equipments,

another group having a plurality of individual electricallyoperable-equipments therein, connectors for establishing circuit pathsbetweenindiyidualequipments of said plurality of groups and individualequipments in said other group,

means in the equipments of said plurality of groups automaticallyenergized by means in said connectors for controlling the choice of acon-

